This invention relates to applicators and/or dispensers for mixing, dispensing and/or applying an adhesive or sealant material, for example, a polymerizable monomer compound such as a cyanoacrylate adhesive or sealant, along with another material, for example, a polymerization rate modifier such as an initiator, particularly for medical use.
Numerous swabs, applicators, dispensers and kits for dispensing and applying various materials, including adhesive or sealant materials, are known. However, these known arrangements possess various shortcomings that make them undesirable in many applications.
Monomer and polymer adhesives or sealants are used in both industrial (including household) and medical applications. Included among these adhesives or sealants are the 1,1-disubstituted ethylene monomers and polymers, such as the α-cyanoacrylates. Since the discovery of the adhesive or sealant properties of such monomers and polymers, they have found wide use due to the speed with which they cure, the strength of the resulting bond formed, and their relative ease of use. These characteristics have made the α-cyanoacrylate adhesives or sealants the primary choice for numerous applications such as bonding plastics, rubbers, glass, metals, wood, and, more recently, biological tissues.
Medical applications of 1,1-disubstituted ethylene monomer adhesive or sealant compositions include use as an alternate or an adjunct to surgical sutures and staples in wound closure as well as for covering and protecting tissue wounds such as lacerations, abrasions, burns, stomatitis, sores, and other open surface wounds. When such an adhesive or sealant is applied, it is usually applied in its monomeric form, and the resultant polymerization gives rise to the desired adhesive or sealant bond.
Applicators for dispensing a polymerizable and/or cross-linkable material, such as a 1,1-disubstituted ethylene formulation, are disclosed in U.S. Pat. No. 5,928,611 to Leung and copending U.S. patent application Ser. No. 09/430,177, filed Oct. 29, 1999. In general, many different 1,1-disubstituted ethylene formulations are known for various applications, for example, cyanoacrylate formulations used as fast-acting surgical adhesive or sealants, bioactive agent release matrixes and implants utilized in medical, surgical and other in vivo applications. Such formulations include those disclosed by Leung and the references cited therein.
However, due to the need to apply the adhesive or sealant in its monomeric form, and due to the rapid polymerization rate of the monomers, it has been very difficult to design effective and commercially viable applicators and/or dispensers. Such applicators and/or dispensers must counterbalance the competing requirements that the monomer not prematurely polymerize, that the monomer be easily applied, that the monomer polymerize at a desired rate upon application, and that the sanitary and/or sterile properties of the monomer and applicator—whether real or perceived—be maintained. This latter requirement, that the actual or perceived sanitary and sterile condition of the monomer and applicator be maintained, is particularly important in medical applications, where the user and/or the patient desires a clean product so as not to introduce further bacteria or foreign matter into a wound site.
A further problem in addressing the above requirements of adhesive or sealant applicators and/or dispensers is the need to provide a stable monomer product. Particularly in small quantities, cyanoacrylate monomers are prone to premature polymerization, which would render the product useless. Thus, industrial production of monomeric adhesive or sealant compositions has had to balance rapid cure rates and high bond strengths with shelf-life. The shelf-life of these adhesives or sealants is primarily related to stability (i.e., constancy of compositional nature), uncured physical properties, rate of cure of the adhesive or sealant, as well as final cured properties of the composition. For example, the shelf-life of a monomeric α-cyanoacrylate composition may be measured as a function of the amount of time the composition can be stored before unacceptable levels of polymerization, such as measured by viscosity increase, occur. Unacceptable levels are indicated by a level of polymerization product that reduces the usefulness of the composition in the application for which it is produced.
Additional problems with known applicators and/or dispensers include, for example, the adhesive or sealant being fed from the applicator/dispenser by gravity only. Such gravity feed methods do not allow for desired control over the flow of the adhesive or sealant from the applicator/dispenser during use. Furthermore, known applicators/dispensers do not allow for fine control over and placement of the adhesive or sealant at the time of use.
Known devices fail to provide an applicator and/or dispenser that is optimized for convenient dispensing and application of adhesive or sealant materials on a variety of surfaces and structures. The known applicators are generally either optimized for delivery of other compositions or are inconvenient for use in conjunction with adhesives or sealants. Furthermore, such conventional devices generally do not address the competing needs of ease of use and adhesive or sealant stability prior to application.